Field of the Invention
The present invention relates to a developing apparatus to be used in an image forming apparatus such as a copying machine, a printer, and a facsimile machine, and more particularly, to a configuration of a blade configured to contact a developer carrying member in a developing container.
Description of the Related Art
In a developing container of an image forming apparatus configured to form images with developer, there is provided a developing blade configured to regulate an amount of the developer so that the developer carried on a surface of a developing sleeve has a uniform constant thickness. The developing blade contacts the developing sleeve, and is formed of an elastic member in many cases. Further, in order to generate a predetermined pressure, the developing blade is arranged in a manner that an opposite surface of the developing blade to a surface of the developing blade contacting the developing sleeve is in contact with a pressing member such as a thin plate member.
The developing blade is mounted to the developing container by a holding member (Japanese Patent Application Laid-Open No. 2011-150269).
However, at a contact portion between the developing blade and the developing sleeve, in a case where the developing blade and the developing sleeve do not uniformly contact each other in a longitudinal direction of the developing blade, the developer on the surface of the developing sleeve cannot be made uniform in thickness. As a result, images of output printed materials are adversely affected. Thus, the developing blade and the developing sleeve need to contact each other without a gap at a uniform pressure in the longitudinal direction. However, the developing blade is formed of an elastic member, and hence has a micro distortion in itself. The micro distortion forms a gap in the contact portion.
It may be conceived to employ a method of increasing contact pressure to be applied between the developing blade and the developing sleeve so that the gap is closed. However, the method shortens a lifetime of the developing blade. As a result, a replacement cycle of the developing container is shortened, which results also in a cost increase.